Change ListContainer::AppendByMoving to return a pointer to the new item

cc/base/list_container.h

Index: cc/base/list_container.h
diff --git a/cc/base/list_container.h b/cc/base/list_container.h
index a9444cd03aa08d1e1192e625198e8222dae0ce36..7cccc6707c4e67ad51af61e045119eace5866ffb 100644
--- a/cc/base/list_container.h
+++ b/cc/base/list_container.h
@@ -296,14 +296,16 @@ class ListContainer : public ListContainerBase {
   // Appends a new item without copying. The original item will not be
   // destructed and will be replaced with a new DerivedElementType. The
   // DerivedElementType does not have to match the moved type as a full block
-  // of memory will be moved (up to MaxSizeForDerivedClass()).
+  // of memory will be moved (up to MaxSizeForDerivedClass()). A pointer to
+  // the moved element is returned.
   template <typename DerivedElementType>
-  void AppendByMoving(DerivedElementType* item) {
+  DerivedElementType* AppendByMoving(DerivedElementType* item) {
     size_t max_size_for_derived_class = MaxSizeForDerivedClass();
     void* new_item = Allocate(max_size_for_derived_class);
     memcpy(new_item, static_cast<void*>(item), max_size_for_derived_class);
     // Construct a new element in-place so it can be destructed safely.
     new (item) DerivedElementType;
+    return static_cast<DerivedElementType*>(new_item);
   }
 
   using ListContainerBase::size;